Redundant appliance configuration repository in standard hierarchical format

ABSTRACT

A configuration of a first storage resource is written to a first instance of a single file in a standard hierarchical format that is stored locally in nonvolatile memory and updatable by the first resource. A configuration of a second storage resource is written to a second instance of the single file in the standard hierarchical format stored locally in nonvolatile memory and updatable by the second resource. The first instance and second instance of the single file are updated so that all configurations are present and identical in all instances of the single file.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 to U.S. Provisional Application No. 60/714,426, filed Sep. 6, 2005, which is herein incorporated by reference in its entirety.

This application contains subject matter which is related to the subject matter of the following applications, each of which is assigned to the same assignee as this application and filed on the same day as this application. Each of the below listed applications is hereby incorporated herein by reference in its entirety:

U.S. patent application Ser. No. ______, by Kirill Malkin, entitled “STORAGE RESOURCE SCAN” (Attorney Docket No. 2660.001A)

U.S. patent application Ser. No. ______, by Malkin et al., entitled “LIGHTWEIGHT MANAGEMENT AND HIGH AVAILABILITY CONTROLLER” (Attorney Docket No. 2660.003A)

U.S. patent Application Ser. No. ______, by Kirill Malkin, entitled “BLOCK SNAPSHOTS OF iSCSI” (Attorney Docket No. 2660.004A)

U.S. patent application Ser. No. ______, by Kirill Malkin, entitled “GENERATING DIGEST FOR BLOCK RANGE VIA iSCSI” (Attorney Docket No. 2660.005A)

U.S. patent application Ser. No. ______, by Kirill Malkin, entitled “INCREMENTAL REPLICATION USING SNAPSHOTS” (Attorney Docket No. 2660.006A)

U.S. patent Application Ser. No. ______, by Kirill Malkin, entitled “PERFORMANCE IMPROVEMENT FOR BLOCK SPAN REPLICATION” (Attorney Docket No. 2660.007A)

U.S. patent application Ser. No. ______, by Dmitry Fomichev, entitled “REUSING TASK OBJECT AND RESOURCES” (Attorney Docket No. 2660.008A)

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention generally relates to configuration redundancy among like resources on a network. More particularly, the present invention relates to configuration redundancy for like resources on a network by tracking configurations in a distributed file across the resources involved.

2. Background Information

It has been found useful to keep track of the configuration settings for various network resources, for example, network storage appliances. For example, if a given resource fails, a replacement can be provided and configured quickly if the configuration of the failed one is stored and easily accessible. In the case of network storage appliances, configuration settings are frequently stored in nonvolatile memory, such as, for example, compact flash or a USB stick. The nonvolatile nature of the memory provides consistency of the configuration across power cycles.

However, storing the configuration in such nonvolatile memory poses problems when the resource fails. In order to attempt to restore the configuration, the nonvolatile memory would need to be taken to another like operational resource on the network for reading and retrieval of the failed resource's configuration. Such a scenario reduces system performance.

Thus, a need exists for a faster way to access configuration information for system resources on a network.

SUMMARY OF THE INVENTION

Briefly, the present invention satisfies the need for a faster way to access configuration information for system resources on a network by storing configurations for a plurality of system resources in a single repository in a standard hierarchical format that is accessible to the each of the plurality of system resources.

In accordance with the above, it is an object of the present invention to provide a unified way to access configurations for system resources.

The present invention provides, in a first aspect, a method of tracking individual configurations for a plurality of resources on a network. The method comprises writing a configuration of a first resource to a first portion of a first instance of a single file in a standard hierarchical format, wherein the first portion is modifiable by the first resource. The method further comprises writing a configuration of a second resource to a second portion of a second instance of the single file in the standard hierarchical format, wherein the second portion is modifiable by the second resource, and synchronizing the first instance and the second instance.

The present invention provides, in second and third aspects, system and program product for tracking individual configurations for a plurality of like resources on a network, corresponding to the method of the first aspect.

These, and other objects, features and advantages of this invention will become apparent from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an example of two storage appliances coupled to a network operating in accordance with an aspect of the present invention.

FIG. 2 depicts an example of a file comprising configurations for the two storage appliances of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 depicts a network 100 comprising a first network storage appliance 102 and a second network storage appliance 104. The storage appliances are coupled to the rest of the network 106 by some form of network connection, for example, by gigabit Ethernet via network interface cards 108 and 110, and cables 112 and 114. The storage appliances also each comprise at least one CPU (116 and 118), random access memory (120 and 122), nonvolatile local storage in the form of a compact flash card (124 and 126), and of course network accessible data storage (128 and 130). Input to and output from the appliances to an operator is provided through I/O (132 and 134), for example, a screen and input mechanism (e.g., buttons or a navigation/select mechanism such as keyboard or keyboard and mouse).

As one skilled in the art will understand, network storage appliances 102 and 104 are essentially limited purpose generic computing devices. Stored in storage 128 and 130 is an operating system, for example, UNIX or a UNIX derivative, preferably LINUX or a customized version of LINUX, along with one or more software programs held in storage that, together with the operating system and CPU, control the operation of the storage appliance. Each appliance is capable of generating, parsing and modifying files in a standard hierarchical format described in more detail below.

The operation of the network storage appliances in accordance with the present invention will now be described with reference to FIGS. 1 and 2. Assume that the storage appliances are part of a cluster with peer-to-peer communications between members of the cluster. On startup of each of the network storage appliances, a control program stored in storage 128 and 130 causes the respective appliance to obtain a single file (e.g. file 200) stored in the respective compact flash. The locally stored single file is in a standard hierarchical format and contains a section for each of the appliances (e.g., sections 202 and 204), each section containing a configuration for the respective appliance. Each configuration has a version (e.g., version number) that is updated whenever a modification to the configuration is made. Except during synchronization, each appliance can only modify its own configuration section in the local instance of the single file. When a given appliance in the cluster is communicating with another, it can receive the configuration of the other, and replace the section of its own standard hierarchical format single file corresponding to the other appliance's configuration. Similarly, the other appliance can receive and replace the configuration for the given appliance.

As noted above, the single file for the configurations is in a standard hierarchical format. Any standard hierarchical format now known or later developed can be used, so long as it has (or can be made to have) a flexible and extensible hierarchical data organization with hierarchically interconnected (e.g., nested) nodes (e.g., objects), each node having attributes or properties. A strong hierarchy allows for specifying multiple configurations and for easily introducing diverse nodes, without complicating the navigation of the file. Perhaps the best currently known example of such a standard hierarchical format, and the preferred format, is XML. Another example is the “ini” format, though well-known “tricks” to allow for nesting would need to be applied. For example, since the beginning of the next section is also the end of the previous, i.e., no breaks, nesting can be simulated by declaring subsections and paragraphs in the following manner: [section-name.subsection-name.paragraph . . . ]. While the “ini” format is not preferred, and can quickly become unruly with nesting, in theory it could be used.

Returning now to the operational description, after placing a copy of the single file in RAM (e.g., appliance 102 placing a copy of the file from compact flash 124 into RAM 120), the storage appliances parse their respective section and configure themselves accordingly. During operation of the system appliances, the configurations may change. Whenever a configuration is modified by an appliance, the modified single file is written locally back to compact flash. This may also be done at predetermined intervals. Whenever a configuration is modified, and preferably at predetermined intervals as well, the appliances compare versions for all configurations and update as necessary. In other words, the various instances of the single file are synchronized across the network resources involved. Synchronization can be done in any number of ways from simple copying to the more complex example provided below. The configurations migrate to other instances, so that all become identical and include all configurations for all members of the group.

One example of synchronizing the single configuration files of the appliances in the cluster will now be provided. Each portion of the file that represents the configuration of an appliance is versioned. When the appliance changes its own configuration, the version is updated, for example, incremented. During a communication session, the communicating appliances compare the version of their own configuration in their local configuration file to that stored in the peer appliance. Normally, the version stored locally would be equal to or greater than the version at the peer. If it is equal, there is no need to replace the configuration. If it is greater, then the configuration is sent to the peer, and it should replace the corresponding portion in its XML. This approach can be thought of as each appliance updating its own configuration everywhere.

The appliances launch communication sessions based on, for example, a modified round-robin algorithm. Each appliance tries to establish a session with all other N−1 appliances in the cluster. If during the round-robin pass, appliance i detects that is has already communicated with appliance j, i.e. j contacted i before i contacted j, then it skips to the next appliance (j+1). That way, appliance i is guaranteed that all appliances communicate, but no communication occurs twice during a given pass.

The description above assumes that both appliances 102 and 104 have previously been joined to the group. Joining an appliance to a group can be accomplished, for example, manually by an administrator via the appliance itself through input/output means, or via a computing unit coupled to the appliance, either local or remote. The joining is preferably not handled in an automated fashion via software for security reasons, however, it could be. Such a manual configuration includes, for example, assigning the group name to the new appliance, and either providing the new appliance with the portal information (IP address and port) of any of the existing members of the group, or one of the members is provided with portal information of the new appliance. The appliance may then be “discovered” by the group and manually or automatically accepted as a member.

A new appliance is assumed to come from the factory with at least a template configuration stored in its compact flash, which is completed by an operator and loaded into RAM, after which the appliance configures itself. There is then a forced synchronization session so that all members of the group have an updated configuration file that includes the new member. A similar scenario takes place upon removing an appliance from the group; that is, an appliance is removed and a forced synchronization session takes place.

Where an appliance is the first one in a group, there is no group to recognize it. Thus, the appliance should have the capability to start a new configuration group with only its own configuration to be placed in the configuration repository.

It should be noted that top levels of the configuration hierarchy in the configuration repository (the single file) include identification information, such as, for example, group name, time of creation, and appliance serial number. This information helps to resolve conflicts in the case of, for example, duplicate group names, or previously in-synch configurations become out-of-synch (e.g., due to a loss of connectivity). In such a case, the configurations having matching identification information can automatically be resynchronized, and configurations that have different identification information can, for example, be resynchronized manually.

Although the example described herein includes resources of a same type, i.e., network storage resources, with identical functions, it will be understood that the resources need not be of the same type, or, if the same type, need not have identical functions. Of course, all resources included in the single file need to be able to synchronize configurations according to a common algorithm. In addition, a resource of one type will typically not be able to run a configuration for another type of resource, but can still maintain a configuration therefor.

The above-described computing environment and/or computing units are only offered as examples. The present invention can be incorporated and used with many types of computing units, computers, processors, nodes, systems, work stations and/or environments without departing from the spirit of the present invention. Additionally, while some of the embodiments described herein are discussed in relation to network storage appliances, such embodiments are only examples. Other types of network resources and computing environments can benefit from the present invention and, thus, are considered a part of the present invention.

The present invention can include at least one program storage device readable by a machine, tangibly embodying at least one program of instructions executable by the machine to perform the capabilities of the present invention. The program storage device can be provided separately, or as a part of a computing unit.

The figures depicted herein are just exemplary. There may be many variations to these diagrams or the steps (or operations) described therein without departing from the spirit of the invention. For instance, the steps may be performed in a differing order, or steps may be added, deleted or modified. All of these variations are considered a part of the invention.

While several aspects of the present invention have been described and depicted herein, alternative aspects may be effected by those skilled in the art to accomplish the same objectives. Accordingly, it is intended by the appended claims to cover all such alternative aspects as fall within the true spirit and scope of the invention. 

1. A method of tracking individual configurations for a plurality of resources on a network, the method comprising: writing a configuration of a first resource to a first portion of a first instance of a single file in a standard hierarchical format, wherein the first portion is modifiable by the first resource; writing a configuration of a second resource to a second portion of a second instance of the single file in the standard hierarchical format, wherein the second portion is modifiable by the second resource; and synchronizing the first instance and the second instance.
 2. The method of claim 1, wherein writing the configuration of the first resource comprises writing to first nonvolatile storage, and wherein writing the configuration of the second resource comprises writing to second nonvolatile storage.
 3. The method of claim 1, wherein the synchronizing is performed whenever a modification is made to an instance of the single file.
 4. The method of claim 1, wherein the synchronizing is performed at a predetermined time.
 5. The method of claim 1, wherein the standard hierarchical format comprises XML.
 6. The method of claim 1, wherein the first resource and the second resource are a same type of resource.
 7. The method of claim 6, wherein the first resource and second resource each comprise a network storage resource.
 8. The method of claim 6, wherein the standard hierarchical format comprises XML.
 9. The method of claim 8, wherein writing the configuration of the first resource comprises writing to first nonvolatile storage, and wherein writing the configuration of the second resource comprises writing to second nonvolatile storage.
 10. The method of claim 9, wherein the synchronizing is performed at least one of whenever a modification is made to an instance of the single file and at a predetermined time.
 11. A system for tracking individual configurations for a plurality of resources on a network, the system comprising: means for writing a configuration of a first resource to a first portion of a first instance of a single file in a standard hierarchical format, wherein the first portion is modifiable by the first resource; means for writing a configuration of a second resource to a second portion of a second instance of the single file in the standard hierarchical format, wherein the second portion is modifiable by the second resource; and means for synchronizing the first instance and the second instance.
 12. The system of claim 11, wherein the means for writing the configuration of the first resource comprises means for writing to first nonvolatile storage, and wherein the means for writing the configuration of the second resource comprises means for writing to second nonvolatile storage.
 13. The system of claim 11, wherein the means for synchronizing comprises means for synchronizing whenever a modification is made to an instance of the single file.
 14. The system of claim 11, wherein the means for synchronizing comprises means for synchronizing at a predetermined time.
 15. The system of claim 11, wherein the standard hierarchical format comprises XML.
 16. The system of claim 11, wherein the first resource and the second resource are a same type of resource.
 17. The system of claim 16, wherein the first resource and second resource each comprise a network storage resource.
 18. The system of claim 16, wherein the standard hierarchical format comprises XML.
 19. The system of claim 18, wherein the means for writing the configuration of the first resource comprises means for writing to first nonvolatile storage, and wherein the means for writing the configuration of the second resource comprises means for writing to second nonvolatile storage.
 20. The system of claim 19, wherein the means for synchronizing comprises at least one of means for synchronizing whenever a modification is made to an instance of the single file and means for synchronizing at a predetermined time.
 21. At least one program storage device readable by a machine tangibly embodying at least one program of instructions executable by the machine to perform a method of tracking individual configurations for a plurality of resources on a network, the method comprising: writing a configuration of a first resource to a first portion of a first instance of a single file in a standard hierarchical format, wherein the first portion is modifiable by the first resource; writing a configuration of a second resource to a second portion of a second instance of the single file in the standard hierarchical format, wherein the second portion is modifiable by the second resource; and synchronizing the first instance and the second instance.
 22. The at least one program storage device of claim 21, wherein writing the configuration of the first resource comprises writing to first nonvolatile storage, and wherein writing the configuration of the second resource comprises writing to second nonvolatile storage.
 23. The at least one program storage device of claim 21, wherein the synchronizing is performed whenever a modification is made to an instance of the single file.
 24. The at least one program storage device of claim 21, wherein the synchronizing is performed at a predetermined time.
 25. The at least one program storage device of claim 21, wherein the standard hierarchical format comprises XML.
 26. The at least one program storage device of claim 21, wherein the first resource and the second resource are a same type of resource.
 27. The at least one program storage device of claim 26, wherein the first resource and second resource each comprise a network storage resource.
 28. The at least one program storage device of claim 26, wherein the standard hierarchical format comprises XML.
 29. The at least one program storage device of claim 28, wherein writing the configuration of the first resource comprises writing to first nonvolatile storage, and wherein writing the configuration of the second resource comprises writing to second nonvolatile storage.
 30. The at least one program storage device of claim 29, wherein the synchronizing is performed at least one of whenever a modification is made to an instance of the single file and at a predetermined time. 